A passage behind a mirror on the fourth floor, which was caved in as of 1993. It leads to Hogsmeade, but where in Hogsmeade it leads to is unknown. Sirius mentioned that it was large enough for an organization to hold a meeting inside.

A passage beneath a one-eyed witch statue by the stairs to the Defence Against the Dark Arts classroom, leading to the cellar of Honeydukes. Tapping the hump with a wand and speaking aloud the word Dissendium to the witch accesses this passage, the hump on the statue then opens and reveals the hidden passageway.

Peeves is the one who smashed one of the two vanishing cabinets, after being convinced to do so by Nearly Headless Nick